Data Burst Communication Techniques For Mobile Communication Devices Operating In Packet Data Sessions

ABSTRACT

In one illustrative example, a mobile communication device receives and decodes a plurality of packet data bursts over a packet data channel of a serving cell. While receiving and decoding the packet data bursts, the mobile communication device also receives and decodes a plurality of broadcast data bursts over a broadcast control channel of a neighbor cell. When a time conflict exists between receiving and decoding at least one of the packet data bursts and receiving and decoding at least one of the broadcast data bursts, the mobile communication device receives and decodes the at least one packet data burst instead of the at least one broadcast data burst when no imminent call drop between the mobile communication device and the serving cell is identified. On the other hand, the mobile communication device receives and decodes the at least one broadcast data burst instead of the at least one packet data burst when an imminent call drop between the mobile communication device and the serving cell is identified.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of and claims priority to U.S.non-provisional patent application having application Ser. No.11/414,568 and filing date of 28 Apr. 2006, now U.S. Pat. No. ______,which is hereby incorporated by referenced herein.

BACKGROUND

1. Field of the Technology

The present disclosure relates generally to data burst communicationsfor mobile communication devices which operate in packet datacommunication sessions in wireless communication networks (e.g. GSM/GPRSnetworks).

2. Description of the Related Art

A mobile communication device may operate in a wireless communicationnetwork, such as a Global System for Mobile Communications (GSM) networkwhich provides for high-speed data communications with use of GeneralPacket Radio Service (GPRS). During a packet data communication session,the mobile device operates to receive data packets over a packet datatraffic channel (PDTCH) of the wireless network. If the mobile devicedetects that a neighbor cell has a stronger radio signal strengthindication (RSSI) than its current serving cell, it may need to behanded-off to the neighbor cell. So that it may receive information overa broadcast control channel (BCCH) or packet BCCH (PBCCH) of the handoffcandidate neighbor cell, the mobile device operates to suspend packetdata transfer operations over the PDTCH without notifying the wirelessnetwork. A selective retransmit scheme of the packet data session issubsequently utilized to receive data blocks missed during thesuspension.

Although all appropriate information is eventually received using thistechnique, it may be very disruptive and wasteful with respect to datathroughput, as data may be transmitted by the wireless network that isnever received by the mobile device. Under some circumstances, it mayeven cause the wireless network to cancel the packet data session due tothe lack of response from the mobile device.

Accordingly, what are needed are improved communication techniquesduring packet data sessions which overcome the deficiencies of the priorart.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of present disclosure will now be described by way ofexample with reference to attached figures, wherein:

FIG. 1 is a block diagram which illustrates pertinent components of amobile station and a wireless communication network;

FIG. 2 is a more detailed diagram of a preferred mobile station of FIG.1;

FIG. 3 is a particular system diagram for the mobile station andwireless network of FIGS. 1 and 2;

FIG. 4 is a flowchart relating to a method of prioritizing thescheduling of different types of data bursts for communication in thewireless communication network;

FIG. 5 is a flowchart relating to a method of scheduling the data burstsfor communication in the wireless communication network (i.e. ascheduling subroutine function for the flowchart of FIG. 4); and

FIGS. 6A-6D are timing diagrams relating to the communication of packetdata bursts over packet data channels and broadcast control data burstsover broadcast control channels.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Data burst communication techniques for mobile communication devicesoperating in packet data sessions are described herein. A mobilecommunication device is adapted to receive and decode packet data of aplurality of packet data bursts of a data block over a packet datachannel during a packet data session. The mobile communication device isfurther adapted to receive and decode broadcast control data of aplurality of broadcast data bursts of the same or adjacent data blockover a broadcast control channel contemporaneously with the receivingand decoding of the packet data, where each broadcast data burst isinterleaved with packet data bursts of the packet data session. When atime conflict between at least one of the packet data bursts and atleast one of the broadcast data bursts exists, the mobile communicationdevice is adapted to prioritize the receiving and decoding of the atleast one packet data burst over the at least one broadcast data burst.However, if the at least one broadcast data burst is from a “highpriority” or “imminent” handoff candidate neighbor cell, the mobilecommunication device is adapted to prioritize the receiving and decodingof the at least one broadcast data burst over the at least one packetdata burst without completely suspending packet transfer operations.Advantageously, an efficient and less disruptive communication techniqueis provided during packet data sessions.

Rather than completely suspend packet data transfer operations toacquire a neighbor cell when it is identified that its systeminformation needs to be urgently received (e.g. a potential imminenthandoff), the mobile device of the present disclosure operates toprioritize the receipt of data bursts on the broadcast control channelof the neighbor cell over data bursts of the packet data transferchannel of the current serving cell. Otherwise, the mobile deviceoperates to prioritize the receipt of data bursts of the packet datatransfer channel over data bursts of the broadcast control channel.Although some data bursts on the packet data transfer channel may bepreempted for data bursts on the broadcast control channel at the timeof the potential imminent handoff, those data bursts of the packet datatransfer channel that do not conflict with the reception of data burstson the broadcast control channel will continue to be received andtransmitted. Thus, while the mobile device examines a high priorityneighbor cell, packet data transfer operations may continue with minimaldata loss only where conflict cannot be avoided.

To illustrate general principles, FIG. 1 shows a block diagram of acommunication system 100 which includes a mobile station 102 (oneexample of a wireless or mobile communication device) which communicatesthrough a wireless communication network 104. Mobile station 102preferably includes a visual display 112, a keyboard 114, and perhapsone or more auxiliary user interfaces (UI) 116, each of which arecoupled to a controller 106. Controller 106 is also coupled to radiofrequency (RF) transceiver circuitry 108 and an antenna 110. Typically,controller 106 is embodied as a central processing unit (CPU) which runsoperating system software in a memory component (not shown). Controller106 will normally control overall operation of mobile station 102,whereas signal processing operations associated with communicationfunctions are typically performed in RF transceiver circuitry 108.Controller 106 interfaces with device display 112 to display receivedinformation, stored information, user inputs, and the like. Keyboard114, which may be a telephone type keypad or full alphanumeric keyboard,is normally provided for entering data for storage in mobile station102, information for transmission to network 104, a telephone number toplace a telephone call, commands to be executed on mobile station 102,and possibly other or different user inputs.

Mobile station 102 sends communication signals to and receivescommunication signals from network 104 over a wireless link via antenna110. RF transceiver circuitry 108 performs functions similar to those ofstation 118 and BSC 120, including for example modulation/demodulationand possibly encoding/decoding and encryption/decryption. It is alsocontemplated that RF transceiver circuitry 108 may perform certainfunctions in addition to those performed by BSC 120. It will be apparentto those skilled in art that RF transceiver circuitry 108 will beadapted to particular wireless network or networks in which mobilestation 102 is intended to operate.

Mobile station 102 includes a battery interface 134 for receiving one ormore rechargeable batteries 132. Battery 132 provides electrical powerto electrical circuitry in mobile station 102, and battery interface 132provides for a mechanical and electrical connection for battery 132.Battery interface 132 is coupled to a regulator 136 which regulatespower to the device. When mobile station 102 is fully operational, an RFtransmitter of RF transceiver circuitry 108 is typically keyed or turnedon only when it is sending to network, and is otherwise turned off toconserve resources. Similarly, an RF receiver of RF transceivercircuitry 108 is typically periodically turned off to conserve poweruntil it is needed to receive signals or information (if at all) duringdesignated time periods.

Mobile station 102 operates using a Subscriber Identity Module (SIM) 140which is connected to or inserted in mobile station 102 at a SIMinterface 142. SIM 140 is one type of a conventional “smart card” usedto identify an end user (or subscriber) of mobile station 102 and topersonalize the device, among other things. Without SIM 140, the mobilestation terminal is not fully operational for communication throughwireless network 104. By inserting SIM 140 into mobile station 102, anend user can have access to any and all of his/her subscribed services.SIM 140 generally includes a processor and memory for storinginformation. Since SIM 140 is coupled to SIM interface 142, it iscoupled to controller 106 through communication lines 144. In order toidentify the subscriber, SIM 140 contains some user parameters such asan International Mobile Subscriber Identity (IMSI). An advantage ofusing SIM 140 is that end users are not necessarily bound by any singlephysical mobile station. SIM 140 may store additional user informationfor the mobile station as well, including datebook (or calendar)information and recent call information.

Mobile station 102 may consist of a single unit, such as a datacommunication device, a cellular telephone, a multiple-functioncommunication device with data and voice communication capabilities, apersonal digital assistant (PDA) enabled for wireless communication, ora computer incorporating an internal modem. Alternatively, mobilestation 102 may be a multiple-module unit comprising a plurality ofseparate components, including but in no way limited to a computer orother device connected to a wireless modem. In particular, for example,in the mobile station block diagram of FIG. 1, RF transceiver circuitry108 and antenna 110 may be implemented as a radio modem unit that may beinserted into a port on a laptop computer. In this case, the laptopcomputer would include display 112, keyboard 114, one or more auxiliaryUIs 116, and controller 106 embodied as the computer's CPU. It is alsocontemplated that a computer or other equipment not normally capable ofwireless communication may be adapted to connect to and effectivelyassume control of RF transceiver circuitry 108 and antenna 110 of asingle-unit device such as one of those described above. Such a mobilestation 102 may have a more particular implementation as described laterin relation to mobile station 402 of FIG. 2.

Mobile station 102 communicates in and through wireless communicationnetwork 104. Wireless communication network 104 may be a cellulartelecommunications network. In the embodiment of FIG. 1, wirelessnetwork 104 is configured in accordance with General Packet RadioService (GPRS) and a Global Systems for Mobile (GSM) technologies.Wireless network 104 includes a base station controller (BSC) 120 withan associated tower station 118, a Mobile Switching Center (MSC) 122, aHome Location Register (HLR) 132, a Serving General Packet Radio Service(GPRS) Support Node (SGSN) 126, and a Gateway GPRS Support Node (GGSN)128. MSC 122 is coupled to BSC 120 and to a landline network, such as aPublic Switched Telephone Network (PSTN) 124. SGSN 126 is coupled to BSC120 and to GGSN 128, which is in turn coupled to a public or privatedata network 130 (such as the Internet). HLR 132 is coupled to MSC 122,SGSN 126, and GGSN 128.

Station 118 is a fixed transceiver station, and station 118 and BSC 120may be referred to as transceiver equipment. The transceiver equipmentprovides wireless network coverage for a particular coverage areacommonly referred to as a “cell”. The transceiver equipment transmitscommunication signals to and receives communication signals from mobilestations within its cell via station 118. The transceiver equipmentnormally performs such functions as modulation and possibly encodingand/or encryption of signals to be transmitted to the mobile station inaccordance with particular, usually predetermined, communicationprotocols and parameters, under control of its controller. Thetransceiver equipment similarly demodulates and possibly decodes anddecrypts, if necessary, any communication signals received from mobilestation 102 within its cell. Communication protocols and parameters mayvary between different networks. For example, one network may employ adifferent modulation scheme and operate at different frequencies thanother networks.

The wireless link shown in communication system 100 of FIG. 1 representsone or more different channels, typically different radio frequency (RF)channels, and associated protocols used between wireless network 104 andmobile station 102. An RF channel is a limited resource that must beconserved, typically due to limits in overall bandwidth and a limitedbattery power of mobile station 102. Those skilled in art willappreciate that a wireless network in actual practice may includehundreds of cells, each served by a station 118 (i.e. or stationsector), depending upon desired overall expanse of network coverage. Allpertinent components may be connected by multiple switches and routers(not shown), controlled by multiple network controllers.

For all mobile station's 102 registered with a network operator,permanent data (such as mobile station 102 user's profile) as well astemporary data (such as mobile station's 102 current location) arestored in HLR 132. In case of a voice call to mobile station 102, HLR132 is queried to determine the current location of mobile station 102.A Visitor Location Register (VLR) of MSC 122 is responsible for a groupof location areas and stores the data of those mobile stations that arecurrently in its area of responsibility. This includes parts of thepermanent mobile station data that have been transmitted from HLR 132 tothe VLR for faster access. However, the VLR of MSC 122 may also assignand store local data, such as temporary identifications. Optionally, theVLR of MSC 122 can be enhanced for more efficient co-ordination of GPRSand non-GPRS services and functionality (e.g. paging forcircuit-switched calls which can be performed more efficiently via SGSN126, and combined GPRS and non-GPRS location updates).

Serving GPRS Support Node (SGSN) 126 is at the same hierarchical levelas MSC 122 and keeps track of the individual locations of mobilestations. SGSN 126 also performs security functions and access control.Gateway GPRS Support Node (GGSN) 128 provides interworking with externalpacket-switched networks and is connected with SGSNs (such as SGSN 126)via an IP-based GPRS backbone network. SGSN 126 performs authenticationand cipher setting procedures based on the same algorithms, keys, andcriteria as in existing GSM. In conventional operation, cell selectionmay be performed autonomously by mobile station 102 or by thetransceiver equipment instructing mobile station 102 to select aparticular cell. Mobile station 102 informs wireless network 104 when itreselects another cell or group of cells, known as a routing area.

In order to access GPRS services, mobile station 102 first makes itspresence known to wireless network 104 by performing what is known as aGPRS “attach”. This operation establishes a logical link between mobilestation 102 and SGSN 126 and makes mobile station 102 available toreceive, for example, pages via SGSN, notifications of incoming GPRSdata, or SMS messages over GPRS. In order to send and receive GPRS data,mobile station 102 assists in activating the packet data address that itwants to use. This operation makes mobile station 102 known to GGSN 128;interworking with external data networks can thereafter commence. Userdata may be transferred transparently between mobile station 102 and theexternal data networks using, for example, encapsulation and tunneling.Data packets are equipped with GPRS-specific protocol information andtransferred between mobile station 102 and GGSN 128.

Those skilled in art will appreciate that a wireless network may beconnected to other systems, possibly including other networks, notexplicitly shown in FIG. 1. A network will normally be transmitting atvery least some sort of paging and system information on an ongoingbasis, even if there is no actual packet data exchanged. Although thenetwork consists of many parts, these parts all work together to resultin certain behaviours at the wireless link.

FIG. 2 is a detailed block diagram of a preferred mobile station 202 ofthe present disclosure. Mobile station 202 is preferably a two-waycommunication device having at least voice and advanced datacommunication capabilities, including the capability to communicate withother computer systems. Depending on the functionality provided bymobile station 202, it may be referred to as a data messaging device, atwo-way pager, a cellular telephone with data messaging capabilities, awireless Internet appliance, or a data communication device (with orwithout telephony capabilities). Mobile station 202 may communicate withany one of a plurality of fixed transceiver stations 200 within itsgeographic coverage area.

Mobile station 202 will normally incorporate a communication subsystem211, which includes a receiver 212, a transmitter 214, and associatedcomponents, such as one or more (preferably embedded or internal)antenna elements 216 and 218, local oscillators (LOs) 213, and aprocessing module such as a digital signal processor (DSP) 220.Communication subsystem 211 is analogous to RF transceiver circuitry 108and antenna 110 shown in FIG. 1. As will be apparent to those skilled infield of communications, particular design of communication subsystem211 depends on the communication network in which mobile station 202 isintended to operate.

Mobile station 202 may send and receive communication signals over thenetwork after required network registration or activation procedureshave been completed. Signals received by antenna 216 through the networkare input to receiver 212, which may perform such common receiverfunctions as signal amplification, frequency down conversion, filtering,channel selection, and like, and in example shown in FIG. 2,analog-to-digital (A/D) conversion. A/D conversion of a received signalallows more complex communication functions such as demodulation anddecoding to be performed in DSP 220. In a similar manner, signals to betransmitted are processed, including modulation and encoding, forexample, by DSP 220. These DSP-processed signals are input totransmitter 214 for digital-to-analog (D/A) conversion, frequency upconversion, filtering, amplification and transmission over communicationnetwork via antenna 218. DSP 220 not only processes communicationsignals, but also provides for receiver and transmitter control. Forexample, the gains applied to communication signals in receiver 212 andtransmitter 214 may be adaptively controlled through automatic gaincontrol algorithms implemented in DSP 220.

Network access is associated with a subscriber or user of mobile station202, and therefore mobile station 202 requires a Subscriber IdentityModule or “SIM” card 262 to be inserted in a SIM interface 264 in orderto operate in the network. SIM 262 includes those features described inrelation to FIG. 1. Mobile station 202 is a battery-powered device so italso includes a battery interface 254 for receiving one or morerechargeable batteries 256. Such a battery 256 provides electrical powerto most if not all electrical circuitry in mobile station 202, andbattery interface 254 provides for a mechanical and electricalconnection for it. The battery interface 254 is coupled to a regulator(not shown) which provides power V+ to all of the circuitry.

Mobile station 202 includes a microprocessor 238 (which is oneimplementation of controller 106 of FIG. 1) which controls overalloperation of mobile station 202. Communication functions, including atleast data and voice communications, are performed through communicationsubsystem 211. The receiving and decoding technique of the presentdisclosure is generally controlled by microprocessor 238 in connectionwith DSP 220. Microprocessor 238 also interacts with additional devicesubsystems such as a display 222, a flash memory 224, a random accessmemory (RAM) 226, auxiliary input/output (I/O) subsystems 228, a serialport 230, a keyboard 232, a speaker 234, a microphone 236, a short-rangecommunications subsystem 240, and any other device subsystems generallydesignated at 242. Some of the subsystems shown in FIG. 2 performcommunication-related functions, whereas other subsystems may provide“resident” or on-device functions. Notably, some subsystems, such askeyboard 232 and display 222, for example, may be used for bothcommunication-related functions, such as entering a text message fortransmission over a communication network, and device-resident functionssuch as a calculator or task list. Operating system software used bymicroprocessor 238 is preferably stored in a persistent store such asflash memory 224, which may alternatively be a read-only memory (ROM) orsimilar storage element (not shown). Those skilled in the art willappreciate that the operating system, specific device applications, orparts thereof, may be temporarily loaded into a volatile store such asRAM 226.

Microprocessor 238, in addition to its operating system functions,preferably enables execution of software applications on mobile station202. A predetermined set of applications which control basic deviceoperations, including at least data and voice communicationapplications, will normally be installed on mobile station 202 duringits manufacture. A preferred application that may be loaded onto mobilestation 202 may be a personal information manager (PIM) applicationhaving the ability to organize and manage data items relating to usersuch as, but not limited to, e-mail, calendar events, voice mails,appointments, and task items. Naturally, one or more memory stores areavailable on mobile station 202 and SIM 256 to facilitate storage of PIMdata items and other information. The PIM application preferably has theability to send and receive data items via the wireless network. In thepresent disclosure, PIM data items are seamlessly integrated,synchronized, and updated via the wireless network, with the mobilestation user's corresponding data items stored and/or associated with ahost computer system thereby creating a mirrored host computer on mobilestation 202 with respect to such items. This is especially advantageouswhere the host computer system is the mobile station user's officecomputer system. Additional applications may also be loaded onto mobilestation 202 through network, an auxiliary I/O subsystem 228, serial port230, short-range communications subsystem 240, or any other suitablesubsystem 242, and installed by a user in RAM 226 or preferably anon-volatile store (not shown) for execution by microprocessor 238. Suchflexibility in application installation increases the functionality ofmobile station 202 and may provide enhanced on-device functions,communication-related functions, or both. For example, securecommunication applications may enable electronic commerce functions andother such financial transactions to be performed using mobile station202.

In a data communication mode, a received signal such as a text message,an e-mail message, or web page download will be processed bycommunication subsystem 211 and input to microprocessor 238.Microprocessor 238 will preferably further process the signal for outputto display 222 or alternatively to auxiliary I/O device 228. A user ofmobile station 202 may also compose data items, such as e-mail messages,for example, using keyboard 232 in conjunction with display 222 andpossibly auxiliary I/O device 228. Keyboard 232 is preferably a completealphanumeric keyboard and/or telephone-type keypad. These composed itemsmay be transmitted over a communication network through communicationsubsystem 211. For voice communications, the overall operation of mobilestation 202 is substantially similar, except that the received signalswould be output to speaker 234 and signals for transmission would begenerated by microphone 236. Alternative voice or audio I/O subsystems,such as a voice message recording subsystem, may also be implemented onmobile station 202. Although voice or audio signal output is preferablyaccomplished primarily through speaker 234, display 222 may also be usedto provide an indication of the identity of a calling party, duration ofa voice call, or other voice call related information, as some examples.

Serial port 230 in FIG. 2 is normally implemented in a personal digitalassistant (PDA)-type communication device for which synchronization witha user's desktop computer is a desirable, albeit optional, component.Serial port 230 enables a user to set preferences through an externaldevice or software application and extends the capabilities of mobilestation 202 by providing for information or software downloads to mobilestation 202 other than through a wireless communication network. Thealternate download path may, for example, be used to load an encryptionkey onto mobile station 202 through a direct and thus reliable andtrusted connection to thereby provide secure device communication.Short-range communications subsystem 240 of FIG. 2 is an additionaloptional component which provides for communication between mobilestation 202 and different systems or devices, which need not necessarilybe similar devices.

FIG. 3 shows a particular system structure for communicating with amobile station. In particular, FIG. 3 shows basic components of anIP-based wireless data network which may be utilized. A mobile station100 communicates with a wireless packet data network 145, and may alsobe capable of communicating with a wireless voice network (not shown).As shown in FIG. 3, a gateway 140 may be coupled to an internal orexternal address resolution component 335 and one or more network entrypoints 305. Data packets are transmitted from gateway 140, which issource of information to be transmitted to mobile station 100, throughnetwork 145 by setting up a wireless network tunnel 325 from gateway 140to mobile station 100. In order to create this wireless tunnel 325, aunique network address is associated with mobile station 100. In anIP-based wireless network, however, network addresses are typically notpermanently assigned to a particular mobile station 100 but instead aredynamically allocated on an as-needed basis. It is thus preferable formobile station 100 to acquire a network address and for gateway 140 todetermine this address so as to establish wireless tunnel 325.

Network entry point 305 is generally used to multiplex and demultiplexamongst many gateways, corporate servers, and bulk connections such asthe Internet, for example. There are normally very few of these networkentry points 305, since they are also intended to centralize externallyavailable wireless network services. Network entry points 305 often usesome form of an address resolution component 335 that assists in addressassignment and lookup between gateways and mobile stations. In thisexample, address resolution component 335 is shown as a dynamic hostconfiguration protocol (DHCP) as one method for providing an addressresolution mechanism.

A central internal component of wireless data network 345 is a networkrouter 315. Normally, network routers 315 are proprietary to theparticular network, but they could alternatively be constructed fromstandard commercially available hardware. The purpose of network routers315 is to centralize thousands of fixed transceiver stations 320normally implemented in a relatively large network into a centrallocation for a long-haul connection back to network entry point 305. Insome networks there may be multiple tiers of network routers 315 andcases where there are master and slave network routers 315, but in allsuch cases the functions are similar. Often network router 315 willaccess a name server 307, in this case shown as a dynamic name server(DNS) 307 as used in the Internet, to look up destinations for routingdata messages. Fixed transceiver stations 320, as described above,provide wireless links to mobile stations such as mobile station 100.

Wireless network tunnels such as a wireless tunnel 325 are opened acrosswireless network 345 in order to allocate necessary memory, routing, andaddress resources to deliver IP packets. Such tunnels 325 areestablished as part of what are referred to as Packet Data Protocol or“PDP contexts” (i.e. data sessions). To open wireless tunnel 325, mobilestation 100 must use a specific technique associated with wirelessnetwork 345. The step of opening such a wireless tunnel 325 may requiremobile station 100 to indicate the domain, or network entry point 305with which it wishes to open wireless tunnel 325. In this example, thetunnel first reaches network router 315 which uses name server 307 todetermine which network entry point 305 matches the domain provided.Multiple wireless tunnels can be opened from one mobile station 100 forredundancy, or to access different gateways and services on the network.Once the domain name is found, the tunnel is then extended to networkentry point 305 and necessary resources are allocated at each of thenodes along the way. Network entry point 305 then uses the addressresolution (or DHCP 335) component to allocate an IP address for mobilestation 100. When an IP address has been allocated to mobile station 100and communicated to gateway 140, information can then be forwarded fromgateway 140 to mobile station 100.

According to the present disclosure, when it is identified that systeminformation of a neighbor cell needs to be urgently received (e.g. apotential imminent handoff) during a packet data session, the mobiledevice operates to prioritize the receipt of data bursts on thebroadcast control channel (BCCH) of the neighbor cell over data burstsof the packet data traffic channel (PDTCH) of the current serving cell.Otherwise, the mobile device operates to prioritize the receipt of databursts of the PDTCH over data bursts of the BCCH. Although some databursts on the PDTCH may be preempted for data bursts on the BCCH at thetime of the potential imminent handoff, those data bursts of the PDTCHthat do not conflict with the reception of data bursts on the PDTCH willcontinue to be received and transmitted. Thus, while the mobile deviceexamines a high priority neighbor cell, packet data transfer operationsmay continue with minimal data loss only where conflict cannot beavoided.

FIGS. 4 and 5 are flowcharts which help describe the data burstcommunication techniques of the present disclosure. In particular, FIG.4 is a flowchart relating to a method of prioritizing the scheduling ofdifferent types of data bursts for communications in the wirelesscommunication network. FIG. 5 is a flowchart relating to a method ofscheduling the data bursts for communication in the wirelesscommunication network. The techniques described in relation to FIGS. 4and 5 are performed by one or more processors of a mobile communicationdevice (e.g. the mobile station described in relation to FIGS. 1-3). Inparticular, the techniques may be embodied in a computer program productwhich includes a computer readable medium (e.g. memory or computer disk)and computer instructions stored in the computer readable medium whichare executable by the one or more processors for performing thetechniques. Preferably, the techniques described herein are utilizedwithin a GSM/GPRS network. Note that terminology and common practicesassociated with GSM/GPRS may be found in the numerous relatedcommunication standards documents.

Referring to FIG. 4, the mobile device is adapted to regularly orperiodically produce a schedule of communication events for its receiverand transmitter in advance (e.g. a few milliseconds prior to actualreception/transmission). These scheduled events instruct or command thereceiver and transmitter to receive and/or transmit data bursts onspecific channels at particular time periods. Channels of the systemthat are used for reception and transmission are defined by uniquefrequency and time slot combinations. Also, the scheduling is driven atleast in part by the timing dictated by the system. In the presentembodiment (e.g. GSM/GPRS), data bursts repeat at an interval of 4.615milliseconds (msecs) (120/26). To facilitate minimized latency, theschedule is composed of one half of a frame (about 2.3 msecs) at a time.The scheduling algorithm is executed every 2.3 msec to build anadditional 2.3 msecs of scheduling. The scheduling algorithm may bestarted slightly before or after such time, however, so that thescheduling interval always starts and ends at times that are not withina schedulable burst.

Each time the scheduling algorithm is executed, a list of data blocksare considered for scheduling the next upcoming time period. Each datablock may include up to a predetermined number of data bursts toschedule according to a predetermined prioritization scheme. In thepresent embodiment, each data block includes from one (1) to four (4)data bursts for scheduling in such fashion. The predeterminedprioritization scheme according to the present disclosure is as follows:“prioritized” broadcast receive blocks (i.e. prioritized BCCH) ofneighbor cells are given the highest priority, followed by packet datareceive blocks (i.e. downlink PDTCH), followed by packet data transmitblocks (i.e. uplink PDTCH), followed by “non-prioritized” broadcastreceive blocks (i.e. non-prioritized BCCH) of neighbor cells. In thepresent embodiment, the listed order of priority is important to achieveefficient and less disruptive communications. Note that “prioritized” or“urgent” broadcast receive blocks are those broadcasted from a neighborcell that is a likely handoff candidate for an imminent handoff. Forexample, it may be that the current serving cell has a relatively lowreceive signal strength indication (RSSI) and a “call drop” may beimminent, so that an imminent handoff to a neighbor cell may berequired. In this case, an indication of “high priority” or “urgentstatus” is provided in association with the broadcast receive block forthe scheduling algorithm.

Beginning at a start block 402 of FIG. 4 (“Start Build ScheduleSegment”), the processor of the mobile device first identifies whetherthere is any urgent or high priority broadcast information (i.e. highpriority BCCH) that needs to be received from a neighbor cell in theupcoming time period (step 404 of FIG. 4). If there is urgent or highpriority broadcast information to be received at step 404, then theprocessor causes the receipt of such broadcast information from theneighbor cell to be scheduled (step 406 of FIG. 6). This scheduling isperformed by calling the scheduling subroutine function of FIG. 5. Infact, each scheduling requirement needed in upcoming steps 408, 410,412, and 414 is performed by a call to the scheduling subroutinefunction of FIG. 5.

If there is no urgent or high priority broadcast information to bereceived as identified at step 404, or the receipt of such broadcastinformation has already been scheduled at step 406, then processingcontinues at step 408 of FIG. 4. In step 408, the processor of themobile device then schedules any packet data receive blocks (i.e.downlink PDTCH) to be received in the upcoming time period (step 408 ofFIG. 4). Next, the processor of the mobile device schedules any packetdata transmit blocks (i.e. uplink PDTCH) to be transmitted in theupcoming time period (step 410 of FIG. 4). Next, the processor of themobile device schedules any regular priority broadcast information (i.e.regular priority BCCH) to be received in the upcoming time period (step412 of FIG. 4). Finally, the processor of the mobile device schedulesthe reception of RF signals on other identified channels to perform RSSIreadings (step 414 of FIG. 4). Again, in the present embodiment, theorder of prioritization is important to achieve efficient and lessdisruptive communications than conventional techniques. The flowchartends at an end block 416 of FIG. 4 (“Done Build Schedule Segment”).

FIG. 5 is a flowchart relating to a method of scheduling the data burstsfor communications in the wireless communication network. This may bereferred to as the scheduling subroutine function which is called in anyof steps 406, 408, 410, 412, and 414 of FIG. 4. In general, if the datablock has a candidate data burst for scheduling within the currentscheduling interval, it is first tested whether the data burst locationis already occupied by an earlier-scheduled, higher-priority data burst.If the candidate data burst fits into the schedule location, thecandidate data burst is scheduled; if the candidate data burst does notfit into the schedule location, the data block associated with thecandidate data burst is canceled.

Beginning at a start block 502 of FIG. 5 (“Start Schedule Block Part”),the processor of the mobile device examines and identifies whether thedata block has a candidate data burst to be scheduled within the currentscheduling interval (step 504 of FIG. 5). If not, then the flowchartends at an end block 512 of FIG. 5 (“Finish Schedule Block Part”) to“return” to the appropriate step or location in the flowchart of FIG. 4.If there is a candidate data burst to be scheduled in the currentscheduling interval at step 504, then the processor examines andidentifies whether an earlier-scheduled, higher-priority data burst isalready included within the current scheduling interval (step 506 ofFIG. 5). If so, the data block that the candidate data burst isassociated with is canceled (step 508 of FIG. 5) and the flowchart endsat end block 512 for returning to the main scheduling algorithm. If theschedule is free for the current scheduling interval at step 506, thenthe candidate data burst is included within the current schedulinginterface (step 510 of FIG. 5). The flowchart ends at the end block 512to return to the main scheduling algorithm of FIG. 4.

FIGS. 6A-6D are timing diagrams relating to the communication of packetdata bursts of a packet data channel and broadcast control data burstsof a broadcast control channel. These timing diagrams help illustratethe techniques of FIGS. 4-5 and results achieved therefrom. In FIG. 6A,a timing diagram is shown for a plurality of data bursts associated witha downlink packet data traffic channel (PDTCH) 602 and an uplink PDTCH604 for a packet data communication session with a current serving cell.Time progresses from left to right in the figures. Each rectangularblock (rectangular blocks 1, 2, 3, or 4) is indicative of a data burst(e.g. a single data burst for uplink PDTCH 604) or a group ofconsecutive data bursts (e.g. a group of four consecutive data burstsfor downlink PDTCH 602). Each grouping of four data burst blocks isassociated with a data block period (e.g. block periods 1, 2, 3, etc.)as indicated. During steady state communications of the packet datasession, packet data bursts of the downlink and uplink PDTCH 602 and 604are regularly and periodically communicated. Data bursts of uplink PDTCH602 immediately follow data bursts of downlink PDTCH 604. In FIG. 6A, nodata bursts associated with a broadcast control channel (BCCH) are shownfor simplicity.

In FIG. 6B, data bursts associated with a BCCH 650 are included alongwith the data bursts of uplink and downlink PDTCH 602 and 604. Dependingon the number of timeslots used for PDTCH, and the relative timing ofneighbor cell BCCH blocks that must be received, the BCCH blocks may fitinto the schedule without any conflict with PDTCH blocks as shown. Inthis case, data bursts of the BCCH are interleaved in an ideal fashionwith the data bursts of the PDTCH. Thus, the mobile device may operateto receive and decode packet data from packet data bursts on the PDTCHwhile contemporaneously receiving and decoding broadcast data frombroadcast data bursts on the BCCH (normal or prioritized) withoutconflict. As the BCCH block is received from a different neighbor cellhaving a different time base, however, the relative timing of the BCCHblock may be anywhere relative to the PDTCH.

FIG. 6C depicts a case where BCCH bursts over a BCCH 660 of a highpriority neighbor cell that need to be urgently received are in conflictwith anticipated PDTCH bursts of the current serving cell. In blockperiod 1, when a BCCH, burst A conflicts with a downlink PDTCH burst B(which is a later portion of PDTCH data burst block 3) and an uplinkPDTCH burst C, the BCCH burst A is prioritized over the others and isreceived and decoded by the mobile device. As shown, the mobile devicestill also receives and decodes an initial portion of PDTCH data burstblock 3 by reducing the number of slots that need to be received. Forthe uplink PDTCH burst C, the entire uplink item interferes and theremainder of the uplink block is canceled. Thus, no attempt is made toschedule the fourth burst of the uplink PDTCH block in block period 1.

At the start of block period 2 of FIG. 6C, the mobile again attempts toschedule new blocks. Similar to block period 1, when a BCCH burst D inblock period 2 conflicts with a downlink PDTCH burst E (which is a laterportion of PDTCH data burst block 1) and an uplink PDTCH burst F, theBCCH burst D is prioritized over the others and is received and decodedby the mobile device. As shown, the mobile device still also receivesand decodes an initial portion of PDTCH data burst block 1 by reducingthe number of slots that need to be received. For the uplink PDTCH burstF, the entire uplink item interferes and the remainder of the uplinkblock is canceled. No attempt is made to schedule the remaining burstsof the uplink PDTCH block in block period 2. As apparent, thedisturbance associated with the high priority BCCH reception only lastsfor two block periods, and as soon as the BCCH block of four BCCH databursts is received, packet transfer mode continues in full operation(e.g. see block period 3).

Interference is often not as disruptive as described in relation to FIG.6C, which may be considered a fairly disruptive scenario to illustratesome less-than-optimal scenarios. FIG. 6D shows another scenario wherethe timing of the BCCH block over a BCCH 670 to be received is lessdisruptive of communications. In FIG. 6D, when a BCCH burst A in blockperiod 2 conflicts with a downlink PDTCH burst B (which is a laterportion of PDTCH data burst block 2) and an uplink PDTCH burst C, theBCCH burst A is prioritized over the others and is received and decodedby the mobile device. As shown, the mobile device still also receivesand decodes an initial portion of PDTCH data burst block 2 by reducingthe number of slots that need to be received. For the uplink PDTCH burstC, the entire uplink item interferes and the remainder of the uplinkblock 2 is canceled. If reception is good, however, the mobile devicemay successfully decode the BCCH block without receiving all four BCCHbursts, and thereby not require the reception of the fourth and finalBCCH burst of the BCCH block D. In this scenario, only the blocks inblock period 2 were affected, whereas the blocks in block period 3 werecompletely unaffected.

According to the present disclosure, operations of the PDTCH arepartially discontinued only just enough to monitor the BCCH of theneighbor cell if it is a high priority or imminent handoff candidate.Potentials collisions or conflicts between the PDTCH and the BCCH areidentified by the mobile device at the microsecond level, so that if thetimeslots for the PDTCH and neighbour cell BCCH do not conflict, bothmay proceed normally.

Comparing the present techniques with prior art techniques, an efficientand less disruptive communication scheme is provided for packet datasessions. Using prior art techniques, a mobile device operates tocompletely suspend packet data transfer operations over the PDTCH sothat it may receive information over a broadcast control channel (BCCH)or packet BCCH (PBCCH) for a handoff candidate neighbor cell. Aselective retransmit scheme of the packet data session is subsequentlyutilized to receive data blocks missed during the suspension. Althoughall appropriate information is eventually received using this prior arttechnique, it may be very disruptive and wasteful with respect to datathroughput, as data may be transmitted by the wireless network that isnever received by the mobile device. Under some circumstances, it mayeven cause the wireless network to cancel the packet data session due tothe lack of response from the mobile device.

According to the present disclosure, a mobile communication device isadapted to receive and decode packet data of a plurality of packet databursts of a data block over a packet data channel during a packet datasession. The mobile communication device is further adapted to receiveand decode broadcast control data of a plurality of broadcast databursts of the same or adjacent data block over a broadcast controlchannel contemporaneously with the receiving and decoding of the packetdata, where each broadcast data burst is interleaved with packet databursts of the packet data session. When a time conflict between at leastone of the packet data bursts and at least one of the broadcast databursts exists, the mobile communication device is adapted to prioritizethe receiving and decoding of the at least one packet data burst overthe at least one broadcast data burst. However, if the at least onebroadcast data burst is from a “prioritized” or “imminent” handoffcandidate neighbor cell, the mobile communication device is adapted toprioritize the receiving and decoding of the at least one broadcast databurst over the at least one packet data burst. Advantageously, anefficient and less disruptive communication technique is provided duringpacket data sessions.

The above-described embodiments of the present disclosure are intendedto be examples only. For example, although the present disclosuredescribes a technique applicable to a GSM/GPRS network, the technique isalso applicable to other networks such as a CDMA or other suitablenetwork. Those of skill in the art may effect alterations, modificationsand variations to the particular embodiments without departing from thescope of the application. The invention described herein in the recitedclaims intends to cover and embrace all suitable changes in technology.

1. A method in a mobile communication device for communicating in awireless communication network, the method comprising the acts of:receiving and decoding a plurality of packet data bursts over a packetdata channel of a serving cell; while receiving and decoding the packetdata bursts, receiving and decoding a plurality of broadcast data burstsover a broadcast control channel of a neighbor cell; when a timeconflict exists between receiving and decoding at least one of thepacket data bursts and receiving and decoding at least one of thebroadcast data bursts: receiving and decoding the at least one packetdata burst instead of the at least one broadcast data burst when noimminent call drop between the mobile communication device and theserving cell is identified; and receiving and decoding the at least onebroadcast data burst instead of the at least one packet data burst whenan imminent call drop between the mobile communication device and theserving cell is identified.
 2. The method of claim 1, wherein thebroadcast data bursts are received and decoded contemporaneously, in atime-interleaved manner, while receiving and decoding the packet databursts.
 3. The method of claim 1, wherein the plurality of broadcastdata bursts are consecutively broadcasted on the broadcast controlchannel for receipt by the mobile communication device.
 4. The method ofclaim 1, wherein the broadcast control channel is defined by a firstfrequency and time slot combination and the packet data channel isdefined by a second frequency and time slot combination.
 5. The methodof claim 1, further comprising: identifying the imminent call drop whena signal strength measurement of the serving cell of the mobilecommunication device is identified to be low.
 6. The method of claim 1,wherein the wireless communication network comprises a Global Systemsfor Mobile Communications (GSM) network, the packet data channelcomprises a packet data traffic channel (PDTCH), and the broadcastcontrol channel comprises a broadcast control channel (BCCH).
 7. Amobile communication device, comprising: a wireless transceiver which isadapted to operate for communications with a wireless communicationnetwork; one or more processors coupled to the wireless transceiver; theone or more processors being operative to: receive and decode, via thewireless transceiver, a plurality of packet data bursts over a packetdata channel of a serving cell; while receiving and decoding the packetdata bursts, receive and decode, via the wireless transceiver, aplurality of broadcast data bursts over a broadcast control channel of aneighbor cell; when a time conflict exists between receiving anddecoding at least one of the packet data bursts and receiving anddecoding at least one of the broadcast data bursts: receive and decodethe at least one packet data burst instead of the at least one broadcastdata burst when no imminent call drop between the mobile communicationdevice and the serving cell is identified; and receive and decode the atleast one broadcast data burst instead of the at least one packet databurst when an imminent call drop between the mobile communication deviceand the serving cell is identified.
 8. The mobile communication deviceof claim 7, wherein the one or more processors are operative to receiveand decode the broadcast data bursts contemporaneously, in atime-interleaved manner, while receiving and decoding the packet databursts.
 9. The mobile communication device of claim 7, wherein theplurality of broadcast data bursts are consecutively broadcasted on thebroadcast control channel for receipt by the mobile communicationdevice.
 10. The mobile communication device of claim 7, wherein thebroadcast control channel is defined by a first frequency and time slotcombination and the packet data channel is defined by a second frequencyand time slot combination.
 11. The mobile communication device of claim7, wherein the one or more processors are further operative to: identifythe imminent call drop when a signal strength measurement of the servingcell of the mobile communication device is identified to be low.
 12. Themobile communication device of claim 7, wherein the wirelesscommunication network comprises a Global Systems for MobileCommunications (GSM) network, the packet data channel comprises a packetdata traffic channel (PDTCH), and the broadcast control channelcomprises a broadcast control channel (BCCH).
 13. A computer programproduct, comprising; a computer readable medium; computer instructionsstored in the computer readable medium; the computer instructions beingexecutable by one or more processors of a mobile communication devicefor: receive and decode, via the wireless transceiver, a plurality ofpacket data bursts over a packet data channel of a serving cell; whilereceiving and decoding the packet data bursts, receive and decode, viathe wireless transceiver, a plurality of broadcast data bursts over abroadcast control channel of a neighbor cell; when a time conflictexists between receiving and decoding at least one of the packet databursts and receiving and decoding at least one of the broadcast databursts: receive and decode the at least one packet data burst instead ofthe at least one broadcast data burst when no imminent call drop betweenthe mobile communication device and the serving cell is identified; andreceive and decode the at least one broadcast data burst instead of theat least one packet data burst when an imminent call drop between themobile communication device and the serving cell is identified.
 14. Thecomputer program product of claim 13, wherein the computer instructionsare further executable for receiving and decoding the broadcast databursts contemporaneously, in a time-interleaved manner, while receivingand decoding the packet data bursts.
 15. The computer program product ofclaim 13, wherein the plurality of broadcast data bursts areconsecutively broadcasted on the broadcast control channel for receiptby the mobile communication device.
 16. The computer program product ofclaim 13, wherein the broadcast control channel is defined by a firstfrequency and time slot combination and the packet data channel isdefined by a second frequency and time slot combination.
 17. Thecomputer program product of claim 13, wherein the computer instructionsare further executable for identifying the imminent call drop when asignal strength measurement of the serving cell of the mobilecommunication device is identified to be low.
 18. The computer programproduct of claim 13, wherein the wireless communication networkcomprises a Global Systems for Mobile Communications (GSM) network, thepacket data channel comprises a packet data traffic channel (PDTCH), andthe broadcast control channel comprises a broadcast control channel(BCCH).